Golf club

ABSTRACT

A golf club includes a head; a shaft having a tip end and a butt end; and a grip. The golf club has a length of greater than or equal to 45.0 inches. The head has a weight of greater than or equal to 195 g. The golf club has a club moment about a rotation center of less than or equal to 22.74 (kg·cm), the rotation center being a point 100 mm away from a butt end of the grip. The shaft may have a weight of less than or equal to 40 g. The golf club has a weight of greater than or equal to 280 g. A butt end region having a distance from the butt end of the grip of 100 mm or less may have a weight of greater than or equal to 27 g. This golf club can exhibit an on-plane effect.

This application claims priority on Patent Application No. 2019-085575filed in JAPAN on Apr. 26, 2019. The entire contents of this JapanesePatent Application are hereby incorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present disclosure relates to a golf club.

Description of the Related Art

Japanese Patent No. 6305611 (US2019/0009155A1) proposes a golf club thatis capable of improving the stability of swing.

SUMMARY OF THE INVENTION

The inventors of the present disclosure have obtained new knowledge oninfluences of a golf club on swing. It is an object of the presentdisclosure to provide a golf club that is capable of improving swing.

In one aspect, a golf club includes a head; a shaft including a tip endand a butt end; and a grip. The golf club has a length of greater thanor equal to 45.0 inches. The head has a weight of greater than or equalto 195 g. The golf club has a club moment Mc about a rotation center ofless than or equal to 22.74 (kg·cm), the rotation center being a pointthat is 100 mm away from a butt end of the grip.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a golf club according to one embodiment;

FIG. 2 is a cross-sectional view of the golf club shown in FIG. 1, takenin the vicinity of a grip butt end;

FIG. 3 is a partially cut-away perspective view of a weight member;

FIG. 4 shows a state of a golfer in a swinging motion, in the phase of atake-back (backswing) action, viewed from the rear side in the targetdirection;

FIG. 5 is a conceptual diagram for explaining an effect of a weight of abutt end region;

FIG. 6 shows a state of a golfer in a swinging motion, at the top ofswing, viewed from the rear side in the target direction; and

FIG. 7 is a schematic diagram illustrating a method for measuring amoment of inertia of a golf club about a center of gravity of the club.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Knowledge as Basis of PresentDisclosure

The inventors of the present disclosure studied influences of a golfclub on swing. As a result, they have found that a club and hands couldgo out of a swing plane, due to specifications of the club. Further,they have found a golf club that is capable of preventing the club andhands from going out of a swing plane.

The swing plane is a widely known concept for explaining a mechanism ofa swing. Generally, the swing plane is a virtual plane that passesthrough a straight line that connects a ball and a target, as well asboth shoulders (or elbows) at address. It is known that the motion of aclub and hands being on this swing plane stabilizes the path of swing,which is likely to lead to a good shot. The word “hands” used hereinmeans the right and left hands that hold a grip.

From the viewpoint of ease-of-swing, a club has been increasinglylightweighted. In this effort of lightweighting a club, the weight ofthe shaft and grip is reduced. On the other hand, as the reboundperformance deteriorates if the head is too light, the head weight ismaintained at or above a certain level.

It has been considered that whether or not a golfer can make a swing onthe swing plane depends on the golfer's skill. The studies by theinventors of the present disclosure consequently proved that in theconventional lightweighted club, the club and hands tend to go out ofthe swing plane in a swinging motion. The present disclosure is based onthis new knowledge.

Hereinafter, the present disclosure will be described in detailaccording to the preferred embodiments with appropriate references tothe accompanying drawings.

It should be noted that the term “axial direction” used in the presentapplication means the axial direction of the shaft.

FIG. 1 shows an overall view of a golf club 2, which shows an embodimentof the present disclosure. As shown in FIG. 1, the golf club 2 includesa golf club head 4, a shaft 6, a grip 8, and a weight member 10. Theweight member 10 is located inside the grip 8. Further, the golf club 2includes a ferrule 12. Note that the weight member 10 does not have tobe present.

The golf club 2 is a driver (No. 1 wood). Typically, the club as adriver has a length of greater than or equal to 43 inches. Preferably,the golf club 2 is a wood-type golf club.

A bidirectional arrow Lc in FIG. 1 indicates a length of the golf club2. The method for measuring the club length Lc is described below.

The golf club 2 includes a butt end region R1. The butt end region R1 isdefined as a region having a distance from a butt end 8 e of the grip 8of less than or equal to 100 mm. In other words, the butt end region R1is a region that extends from a point P100 that is 100 mm away from thebutt end 8 e of the grip 8 in the axial direction, to the butt end 8 eof the grip 8.

In the present embodiment, the head 4 has a hollow structure. The head 4is of a wood type. The head 4 may be of a hybrid type (utility type).The head 4 may be of an iron type. The head 4 may be of a putter type.Examples of the material for the head 4 include metals and fiberreinforced plastics. Examples of the metals include titanium alloys,pure titanium, stainless steel, and soft iron. Examples of the fiberreinforced plastics include carbon fiber reinforced plastics. The headmay be a composite head that has a metal part and a fiber reinforcedplastic part.

The head 4 is attached to an end on a tip end Tp side of the shaft 6.The grip 8 is attached to an end on a butt end Bt side of the shaft 6.The head 4 has a head weight Wh.

The shaft 6 is formed with a laminate of fiber reinforced resin layers.The shaft 6 is in a tubular form. The shaft 6 has a hollow structure. Asshown in FIG. 1, the shaft 6 includes the tip end Tp and the butt endBt. The tip end Tp is positioned inside the head 4. The butt end Bt ispositioned inside the grip 8.

The shaft 6 has a shaft weight Ws. The shaft 6 has a center of gravityGs. The shaft center of gravity Gs is a center of gravity of the shaft 6when isolated as a single member. The center of gravity Gs is positionedon the axis line of the shaft.

A bidirectional arrow Ls in FIG. 1 indicates a length of the shaft. Theshaft length Ls is a distance in the axial direction from the tip end Tpto the butt end Bt. A bidirectional arrow Ds in FIG. 1 indicates adistance in the axial direction from the shaft center of gravity Gs tothe butt end Bt.

The material of the shaft 6 is a carbon fiber reinforced resin. With aview to reducing the weight, a carbon fiber reinforced resin ispreferable as a material for the shaft 6. The shaft 6 is a so-calledcarbon shaft.

Preferably, the shaft 6 is formed with a cured prepreg sheet. In theprepreg sheet, fibers are substantially oriented in one direction. Sucha prepreg in which fibers are substantially oriented in one direction isalso referred to as UD prepreg. “UD” is an abbreviation of“unidirectional”. A prepreg other than the UD prepreg may be used. Forexample, fibers contained in the prepreg sheet may be woven. The shaft 6may include a metal wire.

The prepreg sheet contains fibers and a resin. This resin is alsoreferred to as a matrix resin. Typically, the fibers are carbon fibers.Typically, the matrix resin is a thermosetting resin.

The shaft 6 is produced by a so-called sheet winding method. In theprepreg, the matrix resin is in a semi-cured state. The shaft 6 isformed by winding and curing a prepreg sheet. The shaft 6 may beproduced by a so-called filament winding method.

As the matrix resin of the prepreg sheet, an epoxy resin, athermosetting resin other than an epoxy resin, or a thermoplastic resin,etc. may be used. From the viewpoint of shaft strength, a preferablematrix resin is an epoxy resin.

The method for producing the shaft 6 is not limited. From the viewpointof design freedom, a shaft produced by the sheet winding method ispreferred. Note that the material for the shaft 6 is not limited. Theshaft 6 may be, for example, a steel shaft.

The grip 8 is a part that a golfer grips in a swinging motion. The grip8 has a grip weight Wg.

Examples of the material of the grip 8 include rubber compositions andresin compositions. Examples of rubber contained in the rubbercomposition include natural rubber (NR), ethylene propylene dienemonomer rubber (EPDM), styrene butadiene rubber (SBR), isoprene rubber(IR), butadiene rubber (BR), chloroprene rubber (CR), and acrylonitrilebutadiene rubber (NBR). In particular, natural rubber, or natural rubberblended with a rubber having excellent affinity for natural rubber, suchas ethylene propylene diene rubber or styrene butadiene rubber, ispreferable. Examples of resin contained in the resin composition includea thermoplastic resin. The thermoplastic resin can be used in injectionforming. This thermoplastic resin is preferably a thermoplasticelastomer, and more preferably a thermoplastic elastomer containing asoft segment and a hard segment. With a view to achieving both of thedesired grip property and the abrasion resistance, urethane-basedthermoplastic elastomer is further preferable. From the viewpoint offormability, EPDM and styrene butadiene rubber are more preferable.

The rubber composition for the grip 8 may be a foam rubber. A foamrubber contains many air bubbles, thereby having a low specific gravity.A foaming agent may be mixed in the foam rubber. One example of thisfoaming agent is a thermally decomposable foaming agent. Examples ofthis thermally decomposable foaming agent include azo compounds such asazodicarbonamide, nitroso compounds such as dinitrosopentamethylenetetramine, and triazole compounds. The foam rubber contributes to thelightweighting of the grip 8.

A plurality of types of rubbers having different expansion ratios may beused. Examples of the rubbers having different expansion ratios mayinclude a non-foam rubber (having an expansion ratio of zero). Byadjusting the arrangement of the plurality of types of rubbers, theposition of a center of gravity of the grip 8, and further, the positionof a center of gravity G2 of a grip-weight portion (to be describedbelow) can be adjusted.

The method for producing the grip 8 is not limited. The grip 8 can beproduced by a known producing method. Examples of the producing methodinclude press-forming and injection forming.

When a plurality of types of rubbers having different expansion ratiosare used, press-forming is preferred. In this case, for example, arubber sheet 1 made of a material formed at a first expansion ratio, anda rubber sheet 2 made of a material formed at a second expansion ratio,are prepared. These sheets are placed at arbitrary positions in a mold,respectively, and are heated and pressurized, whereby press-forming isperformed. In this method, rubbers having different expansion ratios canbe arranged independently and freely.

The weight member 10 is located inside the grip 8. The weight member 10is attached to the shaft 6. The weight member 10 is attached in thevicinity of the butt end Bt of the shaft 6. The weight member 10 isattached in the butt end region R1 described above. An entirety of theweight member 10 is positioned in the butt end region R1. The centerline of the weight member 10 coincides with the center line Z1 of theshaft 6.

The weight member 10 may be attached to the shaft 6, or alternatively,may be attached to the grip 8. The weight member 10 in the presentembodiment is not exposed to outside. At least a part of the weightmember 10 may be exposed to outside.

FIG. 2 is a cross-sectional view of the golf club 2, taken in thevicinity of the butt end Bt of the shaft 6.

The shaft 6 is a pipe having a hollow inside. When viewed in a crosssection taken along a plane perpendicular to the center line of theshaft 6, an outer surface 6 a of the shaft 6 is circular. When viewed inthe cross section taken along a plane perpendicular to the center lineof the shaft 6, an inner surface 6 b of the shaft 6 is circular. Theshaft 6 includes a butt end face 6 c. The butt end face 6 c is an endface of the shaft 6 at the butt end Bt. The butt end face 6 c is anannular surface.

The grip 8 is attached on the butt end Bt side of the shaft 6. The grip8 includes a grip body portion 8 a and an end cap portion 8 b. The gripbody portion 8 a is in a cylindrical shape. The grip body portion 8 aincludes a shaft insertion hole into which the shaft 6 is to beinserted. The end cap portion 8 b closes an opening on one end side ofthe grip body portion 8 a. The end cap portion 8 b forms a butt end face8 c of the grip 8. The grip body portion 8 a includes a taper portionthat tapers off as the proximity to the end face 8 c decreases. On theother end side of the grip body portion 8 a, an opening (not shown) thatallows the shaft 6 to be inserted therethrough is formed. The end capportion 8 b includes a through hole 8 d. The through hole 8 d has afunction of releasing air when the shaft 6 is inserted into the grip 8.

The two-dot chain line in FIG. 2 indicates a boundary k1 between thegrip body portion 8 a and the end cap portion 8 b. This boundary k1 is aplane that is positioned at a butt end of the shaft insertion hole andis perpendicular to the center line Z1. For example, at the position ofthis boundary k1, the grip body portion 8 a and the end cap portion 8 bare separated. The end cap portion 8 b is positioned on the butt end 8 eside with respect to the grip body portion 8 a. In the presentembodiment, the end cap portion 8 b is formed with a non-foam rubberexclusively. On the other hand, the grip body portion 8 a includes afoam rubber portion made of a foam rubber. This foam rubber portioncontains many air bubbles, thereby having a low specific gravity. Theend cap portion 8 b has a specific gravity greater than the specificgravity (average specific gravity) of the grip body portion 8 a. Thisconfiguration makes a contribution in allowing the center of gravity ofthe grip 8 to be set closer to the butt end 8 e.

FIG. 3 is a perspective view of the weight member 10.

The weight member 10 includes a weight body 20 and a cover member 30.The weight body 20 is made of a metal. The cover member 30 is made of arubbery elastomer. The weight body 20 can be formed by casting, forging,sintering, die casting, press forming, or the like. The cover member 30can be formed by injection forming, or the like. With use of a mold inwhich a formed weight body 20 is set, the cover member 30 can be formedby injection forming. Alternatively, the weight body 20 and the covermember 30, which are formed separately, can be joined to each other.

The metal material for the weight body 20 is not limited particularly.With a view to obtaining the effect of being on the swing plane (alsoreferred to as an “on-plane effect”, which is to be described below)with a small volume, the weight body 20 preferably has a specificgravity of greater than or equal to 5.0, more preferably greater than orequal to 7.0, and further preferably greater than or equal to 8.0. Fromthe viewpoint of the cost and the formability, the weight body 20preferably has a specific gravity of less than or equal to 20, morepreferably less than or equal to 18, and further preferably less than orequal to 15. In the present embodiment, brass is used for forming theweight body 20. An alloy containing tungsten and nickel can also be usedfavorably.

With a view to increasing a weight W1 of the butt end region R1, theweight of the weight member 10 is preferably greater than or equal to 6g, more preferably greater than or equal to 8 g, and further preferablygreater than or equal to 10 g. With a view to preventing a club weightWe from becoming excessively great, the weight of the weight member 10is preferably less than or equal to 25 g, more preferably less than orequal to 20 g, and further preferably less than or equal to 15 g.

The weight body 20 includes a first end face 22, a second end face 24,and an outer circumferential surface 26. The first end face 22 ispositioned on the tip end Tp side, and the second end face 24 ispositioned on the butt end Bt side, in the shaft axial direction. In thepresent embodiment, the first end face 22 and the second end face 24 areformed by planes perpendicular to the shaft axial direction; however,these are not limited to such configurations.

The outer circumferential surface 26 of the weight body 20 is acylindrical surface. The center line of the outer circumferentialsurface 26 coincides with the center line Z1 of the shaft 6. A throughhole 28 extending in the shaft axial direction is formed in the weightbody 20. Therefore, the weight body 20 in the present embodiment isformed in a cylindrical shape.

The cover member 30 covers the weight body 20. The cover member 30 ismade of a rubbery elastomer. The rubbery elastomer is a material havinga rubbery elasticity, and examples of the same include a vulcanizedrubber, as well as resin-based materials. The cover member 30 in thepresent embodiment is made of a vulcanized rubber.

The cover member 30 includes a side cover 32, a first end cover 34, asecond end cover 36, and a flange portion 38. The side cover 32 coversthe outer circumferential surface 26 of the weight body 20. The sidecover 32 covers an entirety of the outer circumferential surface 26 ofthe weight body 20. The side cover 32 is configured to cover an entiretyin the circumferential direction and in the shaft axial direction of theouter circumferential surface 26 of the weight body 20. The side cover32 is in a cylindrical shape.

The first end cover 34 is continuous with the side cover 32. The firstend cover 34 covers the first end face 22 of the weight body 20. Thefirst end cover 34 covers a part of the first end face 22 of the weightbody 20. Furthermore, a first through hole 40 that is continuous withthe center through hole 28 in the weight body 20 is formed in the firstend cover 34. The center line of the first through hole 40 coincideswith the center line of the center through hole 28.

The second end cover 36 is continuous with the side cover 32. The secondend cover 36 covers the second end face 24 of the weight body 20. Thesecond end cover 36 covers an entirety of the second end face 24 of theweight body 20. Furthermore, a second through hole 42 that is continuouswith the center through hole 28 in the weight body 20 is formed in thesecond end cover 36. The center line of the second through hole 42coincides with the center line of the center through hole 28.

A weight through hole 44 that penetrates through the weight member 10 iscomposed of the through hole 28 of the weight body 20, the first throughhole 40, and the second through hole 42. As shown in FIG. 2, the weightthrough hole 44 is continuous with the through hole 8 d formed in theend cap portion 8 b.

The flange portion 38 is continuous with the second end cover 36. Theflange portion 38 protrudes from the second end cover 36 toward outsidein the shaft radial direction. The flange portion 38 protrudes towardoutside in the radial direction with respect to the side cover 32. Theflange portion 38 abuts on the butt end face 6 c. The flange portion 38covers the butt end face 6 c of the shaft 6. The flange portion 38covers an entirety of the butt end face 6 c. The flange portion 38 is acontinuous annular portion that is continuous in the shaftcircumferential direction.

The center line of the weight member 10 coincides with the center lineZ1 of the shaft 6, but it is not limited to such a configuration. Theweight member 10 does not have to have a center line. From the viewpointof the uniformity of the weight distribution in the shaftcircumferential direction, the center line of the weight member 10preferably coincides with the center line Z1 of the shaft 6.

In the weight member 10, the outer diameter of the side cover 32 is setso that the weight member 10 can be located inside the shaft 6. Theouter diameter of the flange portion 38 is greater than the innerdiameter of the butt end face 6 c. The flange portion 38 abuts on thebutt end face 6 c. The flange portion 38 is engaged with the butt endface 6 c. With this engagement, the positioning of the weight member 10is achieved. In addition, this engagement allows the weight member 10 tobe prevented from dropping to the inside of the shaft 6. As shown inFIG. 2, the flange portion 38 is interposed between the butt end face 6c and the end cap portion 8 b. The flange portion 38 makes acontribution in surely fixing the weight member 10.

The weight member 10 may be fixed to the shaft 6, or alternatively, maybe fixed to the grip 8, or further alternatively, may be fixed tobetween the shaft 6 and the grip 8. In the present embodiment, theweight member 10 is fixed to the shaft 6. Further, in the flange portion38, the weight member 10 is interposed between the shaft 6 and the grip8. Furthermore, an end face 39 of the weight member 10 on the grip buttend 8 e side is in surface contact with the inner face 8 g of the endcap portion 8 b. These configurations make a contribution in surelyfixing the weight member 10. In a case where the weight member 10 isfixed to the grip 8, for example, the weight member 10 may be embeddedin the end cap portion 8 b of the grip 8. As another example in the samecase, a weight attachment part for the attachment of the weight member10 may be provided on the butt end face 8 c of the grip 8, and theweight member 10 may be attached to this weight attachment part.

A method for attaching the weight member 10 to the golf club 2 is asfollows. First, the shaft 6 to which the grip 8 has not been attached isprepared. To the shaft 6, the golf club head 4 may be attachedpreliminarily. Next, on the butt end Bt side of the shaft 6, the weightmember 10 is inserted. This insertion allows the side cover 32 of theweight member 10 to be located inside the shaft 6. At the same time, theflange portion 38 is engaged on the butt end face 6 c of the shaft 6.Next, the shaft 6 incorporating the weight member 10 is inserted intothe grip 8. Through these steps, the weight member 10 is attached to thegolf club 2. The grip 8 is bonded to the outer surface 6 a of the shaft6, for example, with a double-sided adhesive tape.

The weight member 10 is surely fixed in the butt end region R1.Furthermore, of the weight member 10, contact surfaces with the shaft 6are formed by the cover member 30, which suppresses the occurrence ofstrange sound. The weight member 10 which includes the cover member 30and the weight body 20 located inside the cover member 30 absorbsvibration of the shaft 6, thereby improving feel at impact of the golfclub 2.

The weight member 10 does not have to be present. For example, theweight W1 of the butt end region R1 can be increased by increasing awall thickness of the grip 8 in the butt end region R1. Alternatively,for example, the weight W1 of the butt end region R1 can be increased byusing a non-foam rubber in the end cap portion 8 b. Alternatively, forexample, the weight W1 of the butt end region R1 can be increased byincreasing a thickness of the end cap portion 8 b in the axialdirection.

A bidirectional arrow Da in FIG. 2 indicates a length of the weightmember 10 in the axial direction. With a view to concentrating weight onthe butt end Bt side, the length Da is preferably less than or equal to50 mm, more preferably less than or equal to 45 mm, and furtherpreferably less than or equal to 40 mm. With a view to increasing theweight of the weight member 10, the length Da is preferably greater thanor equal to 5 mm, more preferably greater than or equal to 10 mm, andfurther preferably greater than or equal to 15 mm.

A bidirectional arrow Db in FIG. 2 indicates a distance between the tipend Tp side end of the weight member 10 and the butt end 8 e of the grip8. The distance Db is measured along the axial direction. With a view toconcentrating weight on the butt end Bt side, the distance Db ispreferably less than or equal to 70 mm, more preferably less than orequal to 60 mm, further preferably less than or equal to 50 mm, andstill further preferably less than or equal to 40 mm. With a view toincreasing the weight of the weight member 10, the distance Db ispreferably greater than or equal to 15 mm, more preferably greater thanor equal to 20 mm, and further preferably greater than or equal to 25mm.

The cover member 30 in the present embodiment may have a JIS-A hardnessof, preferably, greater than or equal to 50 degrees and less than orequal to 70 degrees. The hardness being set in the above-described rangeallows the flange portion 38 and the like to maintain a sufficientstrength, while enhancing the vibration absorption effect achieved bythe cover member 30, whereby the feel at impact of the golf club 2 canbe improved. Note that the JIS-A hardness is measured by a Type Adurometer under a temperature environment of 23° C. according toJIS-K6253.

In the present application, a grip-weight portion is defined. The golfclub 2 includes a grip-weight portion 46. The “grip-weight portion 46”is a portion, of the golf club 2, that is constituted by the grip 8 andthe weight member 10. In the grip-weight portion 46, the weight member10 may be in contact with the grip 8, or alternatively, the weightmember 10 does not have to be in contact with the grip 8. Even when theweight member 10 is not in contact with the grip 8, the combination ofthe grip 8 and the weight member 10 is defined as the grip-weightportion 46. It should be noted that the weight member 10 is positionedin the butt end region R1. The grip-weight portion 46 has a weight W2.The grip-weight portion 46 includes a bonding portion (a double-sidedadhesive tape, etc.) that fixes the grip 8 to the shaft 6 and/or thelike. When a bonding portion (an adhesive, etc.) that fixes the weightmember 10 to the shaft 6 and/or the like is present, the grip-weightportion 46 includes this bonding portion. In the present embodiment, anadhesive or the like for fixing the weight member 10 is not used.

In the present application, a shaft-grip-weight portion is defined. Thegolf club 2 includes a shaft-grip-weight portion 48. The“shaft-grip-weight portion 48” is a portion, of the golf club 2, that isconstituted by the shaft 6, the grip 8, and the weight member 10. In theshaft-grip-weight portion 48, the weight member 10 may be in contactwith the grip 8, or alternatively, the weight member 10 does not have tobe in contact with the grip 8. It should be noted that the weight member10 is positioned in the butt end region R1. The shaft-grip-weightportion 48 has a weight W3. The shaft-grip-weight portion 48 includes abonding portion (a double-sided adhesive tape, etc.) that fixes the grip8 to the shaft 6 and/or the like. The shaft-grip-weight portion 48includes a bonding portion (an adhesive, etc.) that fixes the weightmember 10 to the shaft 6 and/or the like. The shaft-grip-weight portion48 does not include a bonding portion (an adhesive, a sleeve, etc.) thatfixes the head 4 to the shaft 6. The shaft-grip-weight portion 48 doesnot include a ferrule.

[1. Relationship Between Specifications of Golf Club and Swing]

The inventors of the present disclosure closely studied swing, based onnew viewpoints. As a result, they have found that the specifications ofa golf club could adversely affect swing. A conventional heavy golf clubcannot increase the head speed, resulting in a short flight distance.From this viewpoint, a lightweight golf club whose parts other than thehead have a reduced weight has been developed. This lightweight golfclub contributes to increased head speed. The inventors of the presentdisclosure, however, have found that this conventional lightweight golfclub could adversely affect swing.

[1-1. Off-Plane Swing Resulting from Specifications of Golf Club]

FIG. 4 shows a state of a golfer 50 in a swinging motion, viewed fromthe rear side in the target direction. FIG. 4 shows a phase in themiddle of a backswing. The golfer 50 in a swinging motion holds the grip8 of the golf club 2 with hands 52. The hands 52 include the right handand the left hand. The hands 52 mean the finger-side portions withrespect to the wrists. In a take-back action (backswing) and adownswing, the golf club 2 is in an obliquely inclined state, with thegrip 8 side being the lower side.

In FIG. 4, a swing plane SP is indicated with a two-dot chain line.Ideal swing planes SP can be found for respective golfers 50. It isknown that a swing in which the golf club 2 and the hands 52 move on theswing plane SP stabilizes the path of swing, which is likely to lead toa good shot. FIG. 4 shows an excellent swing in which the golf club 2and the hands 52 move on the swing plane SP. This excellent swing isalso referred to as an “on-plane swing”.

The force of gravity acting on the head 4 acts downward in the verticaldirection. This force of gravity rotates the golf club 2 around thehands 52 as the fulcrum, acting such that the golf club 2 tends to liedown. As a result, the head side of the golf club 2 tends to go outdownward with respect to the swing plane SP (see the arrow y1 and thetwo-dot chain lines in FIG. 4).

The golf club 2, starting to rotate, has a natural tendency to rotatearound the center of gravity of the golf club 2 as the fulcrum. Thecenter of gravity of the golf club 2 is positioned on the head 4 sidewith respect to the tip end 8 f of the grip 8. The center of gravity ofthe golf club 2 is separated in the axial direction by greater than orequal to 200 mm from the butt end 8 e of the grip 8. When the head sideof the golf club 2 goes downward in the rotation, the grip side of thegolf club 2 is pushed upward. In other words, the hands 52 are pushedupward. As a result, the hands 52 tend to go out upward with respect tothe swing plane SP (see the arrow y2 and the two-dot chain lines in FIG.4). The position of the hands 52 directly affects swing.

It has been found that, in this way, the force of gravity acting on thehead 4 causes the golf club 2 and the hands 52 to go out of the swingplane SP. This phenomenon has been clarified by accurately measuring themotions of golfers and golf clubs in many swing actions. This phenomenonincreases the degree of deviation in positions of the golf club 2 andthe hands 52 from the swing plane SP. In other words, this phenomenoncauses a swing with the golf club 2 and the hands 52 being off the swingplane (hereinafter referred to as an off-plane swing). In this swing,the path of swing and the hitting point tend to vary in each shot.

From the viewpoint of ease-of-swing, a lightweight club having aweight-reduced shaft and grip has been developed. However, since aweight reduction in the head causes a deterioration in reboundperformance, the reduction of the head weight is limited. As a result,even when the club is lightweight, its head has a heavy weight. Asdescribed above, it has been found that such a club tends to cause theabove-defined off-plane swing.

[1-2. On-Plane Effect]

In the present embodiment, a club moment Mc about a point P100 thatserves as a rotation center and that is 100 mm away from the butt end 8e of the grip 8 is decreased.

FIG. 5 shows the same golf club 2 as in FIG. 1. The club moment Mc (kgcm) is calculated by the following formula (1):Mc=Wc×L1  (1),Where We represents the club weight (kg), and L1 is a distance (cm) inthe axial direction from the point P100 to the center of gravity of theclub.

As described above, in a swinging motion, the golf club 2 has a naturaltendency to rotate around the hands 52 as a fulcrum 54, such that thehead side portion of the golf club 2 goes downward. The fulcrum 54 ispositioned in the vicinity of the point P100. The moment of thisrotation is also referred to as “off-plane moment”. The off-plane momentis suppressed by decreasing the club moment Mc. A decrease in the clubmoment Mc prevents the golf club 2 from going out of the swing plane SP.At the same time, the hands 52 are also prevented from going out of theswing plane SP. This advantageous effect is also referred to as theon-plane effect. The on-plane effect decreases the number of missedshots, stabilizes the path of swing, and makes hitting pointsconsistent. As a result, an average flight distance increases, and thehitting point is prevented from varying in each shot. This phenomenonhas been clarified by accurately measuring the motions of golfers andgolf clubs in many swing actions.

A longer golf club can increase the head speed, but at the same time, itis apt to have a larger variation in hitting points. With the golf club2, however, the on-plane effect suppresses the variation in hittingpoints. As a result, consistent hitting points are obtained even whenthe club is long, and an increased head speed resulting from the greaterclub length can also be attained. The average flight distance isconsequently increased further, and the directional stability of hitballs is also attained.

In the present embodiment, the weight W1 of the butt end region R1 isincreased, and thus a force of gravity Fg acts on the center of gravityof the butt end region R1 (see FIG. 5). By increasing the force ofgravity Fg, the club moment Mc is suppressed even with a greater headweight Wh. Furthermore, by decreasing the shaft weight Ws, the clubmoment Ms is suppressed.

[1-3. Club Weight Effect]

FIG. 6 shows a state of the golfer 50 in a swinging motion, viewed fromthe rear side in the target direction. FIG. 6 shows a phase at thetop-of-swing (top).

In the present embodiment, the club weight We is increased. Thus, fromthe top through the former half stage of downswing in a swinging motion,a greater force of gravity acts on the golf club 2, whereby the forceworks to move the golf club 2 downward (the arrow y3 in FIG. 6). Thisdownwardly acting force enables the golfer to easily pull his/her armsdown, thereby causing the path of the grip to pass closer to thegolfer's body. This increases the speed of pulling the arms down in theformer half stage of downswing, whereby increasing the kinetic energy ofthe arms. The kinetic energy of the arms is transmitted to the head 4 ofthe golf club 2 in the latter half stage of downswing, therebyincreasing the head speed.

Further, it has been found that, since the increased club weight Wcenables the golfer to easily pull his/her arms down from the top throughthe former half stage of the downswing, the hands 52 are prevented fromgoing out upward (forward) with respect to the swing plane SP, therebyenabling the golfer to easily perform a swing on the swing plane SP.This on-plane swing stabilizes the path of swing, reduces variation inhitting points, and improves the flight distance and directionalstability of hit balls. This phenomenon has been clarified by accuratelymeasuring the motions of golfers and golf clubs in many swing actions.

These advantageous effects achieved by the increased club weight Wc arereferred to as “club weight effect”. It was considered that the headspeed can be further increased as the club weight is reduced. It hasbeen found that, however, the head speed can be increased by setting theclub weight Wc to greater than or equal to a specified value. The clubweight effect is attained by increasing the club weight Wc anddecreasing the club moment Mc.

[2. Specifications of Golf Club]

Specifications of the golf club 2 that are able to further improve theabove-described advantageous effects are as follows.

[2-1. Club Moment Mc]

As described above, the on-plane effect can be attained by suppressingthe club moment Mc about the rotation center which is the point 100 mmaway from the butt end 8 e of the grip 8 in the axial direction. Fromthis viewpoint, the club moment Mc is preferably less than or equal to22.74 (kg·cm), more preferably less than or equal to 22.73 (kg·cm), andfurther preferably less than or equal to 22.72 (kg·cm). Considering theclub length Lc and the head weight Wh, the club moment Mc is preferablygreater than or equal to 21.00 (kg·cm), more preferably greater than orequal to 21.50 (kg·cm), and further preferably greater than or equal to22.00 (kg·cm).

[2-2. Club Length Lc]

When the club length Lc is long, the path of the head 4 tends to varyparticularly in a direction perpendicular to the swing plane SP.However, the decreased club moment Mc causes the on-plane effect,thereby suppressing the variation in the head path. With a view toincreasing the radius of the head path so as to increase the head speedwhile suppressing the variation in the head path using the on-planeeffect, the club length Lc is preferably greater than or equal to 45.0inches, more preferably greater than or equal to 45.5 inches, andfurther preferably greater than or equal to 45.75 inches. Consideringthe golf rules and the ease-of-swing, the club length Lc is preferablyless than or equal to 48 inches, more preferably less than or equal to47 inches, and further preferably less than or equal to 46 inches.

[2-3. Shaft Weight Ws]

Reduction of the shaft weight Ws makes it possible to suppress the clubmoment Mc. From this viewpoint, the shaft weight Ws is preferably lessthan or equal to 42 g, more preferably less than or equal to 41 g, andfurther preferably less than or equal to 40 g. From the viewpoint of thestrength of the shaft, the shaft weight Ws is preferably greater than orequal to 25 g, more preferably greater than or equal to 30 g, andfurther preferably greater than or equal to 35 g.

[2-4. Head Weight Wh]

By suppressing the club moment Mc, the golf club 2 is prevented fromgoing out of the swing plane SP even with a heavy head 4. With a view toincreasing the kinetic energy of the head 4 and increasing the initialvelocity of a ball while suppressing variation in the head path usingthe on-plane effect, the head weight Wh is preferably greater than orequal to 192 g, more preferably greater than or equal to 195 g, andfurther preferably greater than or equal to 196 g. Considering the clubmoment Mc, the head weight Wh is preferably less than or equal to 210 g,more preferably less than or equal to 205 g, and further preferably lessthan or equal to 200 g.

[2-5. Club Weight Wc]

From the viewpoint of the club weight effect, the club weight Wc ispreferably greater than or equal to 275 g, and more preferably greaterthan or equal to 280 g. It has been found that this club weight Wcenables many of amateur golfers to enjoy the benefits of the club weighteffect. It has been found that this club weight Wc enables relativelypowerless golfers (also referred to as “golfers in Category A”) to whichthe largest number of golfers belong when all golfers are classified toenjoy the benefits of the club weight effect. The golfers in Category Aare golfers who swing a driver at a head speed of 33.0 m/s to 42.0 m/sand have a handicap of greater than or equal to 18 and less than orequal to 36. From the viewpoint of ease-of-swing, the club weight Wc ispreferably less than or equal to 300 g, more preferably less than orequal to 295 g, further preferably less than 295 g, and still furtherpreferably less than or equal to 290 g.

[2-6. Weight W1 in Butt End Region R1]

As described above, the butt end region R1 is a region having a distancefrom a butt end of the golf club 2 in the axial direction of less thanor equal to 100 mm. The weight W1 of the butt end region R1 is a weightof the golf club 2 in the butt end region R1. When the weight member 10is provided in the butt end region R1, the weight W1 includes the weightof the weight member 10. Further, the weight W1 includes the weight ofthe grip 8 in the region R1, and the weight of the shaft 6 in the regionR1. Furthermore, when an adhesive, a double-sided adhesive tape, and/orthe like is present in the butt end region R1, the weight of those isalso included in the weight W1.

With a view to suppressing the club moment Mc to enhance the on-planeeffect, the weight W1 of the butt end region R1 is preferably greaterthan or equal to 27 g, more preferably greater than or equal to 30 g,further preferably greater than or equal to 31 g, still furtherpreferably greater than or equal to 32 g, still further preferablygreater than or equal to 33 g, and still further preferably greater thanor equal to 34 g. With a view to preventing the club weight Wc frombecoming excessively great, the weight W1 of the butt end region R1 ispreferably less than or equal to 70 g, more preferably less than orequal to 60 g, further preferably less than or equal to 50 g, and stillfurther preferably less than or equal to 45 g.

[2-7. Weight W2 of Grip-Weight Portion]

With a view to suppressing the club moment Mc to enhance the on-planeeffect, the weight W2 of the grip-weight portion is preferably greaterthan or equal to 40 g, more preferably greater than or equal to 41 g,and further preferably greater than or equal to 42 g. Considering theclub weight Wc, the weight W2 of the grip-weight portion is preferablyless than or equal to 75 g, more preferably less than or equal to 65 g,further preferably less than or equal to 55 g, and still furtherpreferably less than or equal to 50 g.

[2-8. Weight W3 of Shaft-Grip-Weight Portion]

With a view to making the weight of the shaft 6 lightweight and makingthe grip-weight portion 46 heavier, the weight W3 of theshaft-grip-weight portion is preferably set in a predetermined range.The lower limit value of the range of the weight W3 is preferablygreater than or equal to 75 g, more preferably greater than or equal to78 g, and further preferably greater than or equal to 80 g. The upperlimit value of the range of the weight W3 is preferably less than orequal to 100 g, more preferably less than or equal to 90 g, and furtherpreferably less than or equal to 88 g.

[2-9. W1/W3]

“W1/W3” is a ratio of the weight W1 of the butt end region R1 to theweight W3 of the shaft-grip-weight portion. W1/W3 can be increased byconcentrating weight in the butt end region R1. An increase in W1/W3decreases the club moment Mc, thereby enhancing the on-plane effect.From this viewpoint, W1/W3 is preferably greater than or equal to 0.40,more preferably greater than or equal to 0.41, and further preferablygreater than or equal to 0.42.

Considering the limit of the weight W1 of the butt end region R1, W1/W3is preferably less than or equal to 0.60, more preferably less than orequal to 0.58, and further preferably less than or equal to 0.56.

[2-10. Gravity Center Ratio T3 of Shaft-Grip-Weight Portion]

The shaft-grip-weight portion 48 has a center of gravity G3. Thebidirectional arrow D3 shown in FIG. 5 indicates a distance from thebutt end 8 e of the grip 8 to the center of gravity G3. The distance D3is measured along the axial direction. The bidirectional arrow L3 shownin FIG. 5 indicates a distance from the butt end 8 e of the grip 8 tothe tip end Tp of the shaft 6. The distance L3 is measured along theaxial direction.

The gravity center ratio T3 (%) of the shaft-grip-weight portion 48 iscalculated by (D3/L3)×100. By making the shaft 6 lighter in weight andincreasing the weight W1 of the butt end region R1, the center ofgravity G3 is positioned closer to the butt end Bt, whereby the gravitycenter ratio T3 can be decreased. With a view to decreasing the clubmoment Mc to enhance the on-plane effect, the gravity center ratio T3 ispreferably less than or equal to 30%, more preferably less than or equalto 29%, further preferably less than or equal to 28%, and still furtherpreferably less than or equal to 27%. Considering the limit of theweight W1 of the butt end region R1, the gravity center ratio T3 ispreferably greater than or equal to 20%, more preferably greater than orequal to 22%, and further preferably greater than or equal to 24%.

[2-11. Gravity Center Ratio T2 of Grip-Weight Portion]

The grip-weight portion 46 has a center of gravity G2. The bidirectionalarrow D2 shown in FIG. 5 indicates a distance from the butt end 8 e ofthe grip 8 to the center of gravity G2. The distance D2 is measuredalong the axial direction. The bidirectional arrow L2 shown in FIG. 5indicates a distance from the butt end 8 e of the grip 8 to the tip end8 f of the grip 8. In other words, L2 indicates a length of the grip 8.The distance L2 is measured along the axial direction. The center ofgravity G2 is positioned in the butt end region R1.

The gravity center ratio T2 (%) of the grip-weight portion 46 iscalculated by (D2/L2)×100. By making the grip 8 lighter in weight andincreasing the weight W1 of the butt end region R1, the center ofgravity G2 is positioned closer to the butt end Bt, whereby the gravitycenter ratio T2 can be decreased. With a view to decreasing the clubmoment Mc to enhance the on-plane effect, the gravity center ratio T2 ispreferably less than or equal to 30%, more preferably less than or equalto 29%, and further preferably less than or equal to 28%. Consideringthe limit of the weight W1 of the butt end region R1, the gravity centerratio T2 is preferably greater than or equal to 5%, more preferablygreater than or equal to 10%, and further preferably greater than orequal to 15%.

[2-12. Ws/Wc]

“Ws/Wc” is a ratio of the shaft weight Ws to the club weight Wc. Bydecreasing this ratio, weight can be effectively concentrated in thebutt end region R1. With a view to decreasing the club moment Mc toenhance the on-plane effect, Ws/Wc is preferably less than or equal to0.15, and more preferably less than or equal to 0.145. An excessivelygreat club weight Wc makes the club difficult to swing, which decreasesthe head speed. From this viewpoint, Ws/Wc is preferably greater than orequal to 0.11, more preferably greater than or equal to 0.12, andfurther preferably greater than or equal to 0.13.

[2-13. Wg/W2]

“Wg/W2” is a ratio of the grip weight Wg to the weight W2 of thegrip-weight portion. By decreasing this ratio, weight can be effectivelyconcentrated in the butt end region R1. With a view to decreasing theclub moment Mc to enhance the on-plane effect, Wg/W2 is preferably lessthan or equal to 0.80, more preferably less than or equal to 0.78,further preferably less than or equal to 0.76, and still furtherpreferably less than or equal to 0.74. Wg/W2 is preferably greater thanor equal to 0.50, more preferably greater than or equal to 0.55, andfurther preferably greater than or equal to 0.60.

[2-14. W1/Ws]

“W1/Ws” is a ratio of the weight W1 of the butt end region R1 to theshaft weight Ws. With a view to decreasing the club moment Mc to enhancethe on-plane effect, W1/Ws is preferably greater than or equal to 0.75,more preferably greater than or equal to 0.80, and further preferablygreater than or equal to 0.85. Considering the preferable ranges of W1and Ws, W1/Ws is preferably less than or equal to 1.20, more preferablyless than or equal to 1.10, and further preferably less than or equal to1.00.

[2-15. Grip Weight Wg]

When the weight member 10 is provided, the grip weight Wg is preferablysmaller. By decreasing the grip weight Wg, weight can be effectivelyconcentrated in the butt end region R1, where the weight member 10 islocated. From this viewpoint, the grip weight Wg is preferably less thanor equal to 35 g, more preferably less than or equal to 33 g, andfurther preferably less than or equal to 31 g. From the viewpoint of thestrength of the grip, the grip weight Wg is preferably greater than orequal to 20 g, more preferably greater than or equal to 22 g, andfurther preferably greater than or equal to 24 g.

[2-16. Shaft Gravity Center Distance Ds]

A distance in the axial direction from the center of gravity Gs of theshaft 6 to the butt end Bt of the shaft 6 is defined as the shaftgravity center distance Ds (see FIG. 1). With a view to decreasing theclub moment Mc, the shaft gravity center distance Ds is preferably lessthan or equal to 550 mm, more preferably less than or equal to 545 mm,and further preferably less than or equal to 540 mm. An excessivelysmall shaft gravity center distance Ds reduces weight distribution tothe tip portion of the shaft 6, thereby leading to insufficient strengthof the tip portion. From this viewpoint, the shaft gravity centerdistance Ds is preferably greater than or equal to 400 mm, morepreferably greater than or equal to 450 mm, and further preferablygreater than or equal to 500 mm.

[2-17. Shaft Gravity Center Ratio]

The shaft gravity center ratio is calculated by [(Ls−Ds)/Ls)]×100. Witha view to decreasing the club moment Mc, the shaft gravity center ratiois preferably greater than or equal to 51%, more preferably greater thanor equal to 51.5%, and further preferably greater than or equal to 52%.An excessively small shaft gravity center distance Ds reduces weightdistribution to the tip portion of the shaft 6, thereby leading toinsufficient strength of the tip portion. From this viewpoint, the shaftgravity center ratio is preferably less than or equal to 58%, morepreferably less than or equal to 55%, and further preferably less thanor equal to 54%.

[2-18. Shaft Length Ls]

Considering the preferable range of the club length Lc, the shaft lengthLs is preferably greater than or equal to 44 inches, more preferablygreater than or equal to 44.5 inches, and further preferably greaterthan or equal to 45 inches. Considering the preferable range of the clublength Lc, the shaft length Ls is preferably less than or equal to 47.5inches, more preferably less than or equal to 47 inches, and furtherpreferably less than or equal to 46 inches.

[2-19. Ic/(Lc×Wc)]

Ic represents a moment of inertia of a club about the center of gravityof the club. The unit of the moment of inertia Ic is g·cm². The momentof inertia Ic can be measured by using, for example, MODEL NUMBERRK/005-002 manufactured by INERTIA DYNAMICS. In the calculation ofIc/(Lc×Wc), the unit of the club length Lc is centimeters (cm), and theunit of the club weight We is grams (g). As a result, the unit ofIc/(Lc×Wc) is centimeters (cm).

When the golf club 2 has a greater moment of inertia Ic about its centerof gravity, the behavior of the golf club 2 is stabilized and a swayingmotion of the golf club 2 is suppressed. As a result, variation inhitting points is lessened. A greater club weight We and/or a greaterclub length Lc increases the moment of inertia Ic but impairsease-of-swing. As a result, the head speed is decreased, and the flightdistance is reduced. An increase in Ic/(Lc×Wc) attains an increase inthe moment of inertia Ic with respect to the club weight We and the clublength Lc. An increase in Ic/(Lc×Wc) enables a lightweight club thatdoes not have an excessively long length to have an increased moment ofinertia Ic. As a result, this club is easy to swing and has less swayingmotion. The golf club 2 includes the lightweight shaft 6 and the buttend region R1 having a great weight W1. As a result, in the golf club 2,weight is concentrated in the butt end region R1 and the head 4, therebyattaining an increased Ic/(Lc×Wc).

With a view to obtaining a club that is easy to swing and has lessswaying motion, Ic/(Lc×Wc) is preferably greater than or equal to 15.3cm, more preferably greater than or equal to 15.9 cm, further preferablygreater than or equal to 16.5 cm, further preferably greater than orequal to 16.6 cm, and still further preferably greater than or equal to16.7 cm. Considering the restriction in design of the club, Ic/(Lc×Wc)is preferably less than or equal to 19.0 cm, more preferably less thanor equal to 18.5 cm, and further preferably less than or equal to 18.0cm.

[2-20. Moment of Inertia Ic]

With a view to stabilizing the behavior of the golf club 2 andsuppressing the swaying motion of the golf club 2, the moment of inertiaIc is preferably greater than or equal to 500×10³ (g·cm²), morepreferably greater than or equal to 520×10³ (g·cm²), and furtherpreferably greater than or equal to 540×10³ (g·cm²). Considering therestriction in design of the club, the moment of inertia Ic ispreferably less than or equal to 650×10³ (g·cm²), more preferably lessthan or equal to 630×10³ (g·cm²), and further preferably less than orequal to 610×10³ (g·cm²).

[2-21. Golf Club Number]

The longer a club is, the more importance golfers tend to place on itsflight distance performance. Furthermore, the longer a club is, the moresignificantly the hitting point thereof varies in each shot, resultingin that the direction of a hit ball is hardly stabilized. Negativeproperties of a long club are improved effectively by theabove-described effects. From this viewpoint, a wood-type club ispreferable, and a driver is particularly preferable. The driver has areal loft angle of, usually, greater than or equal to 7° and less thanor equal to 15°. The head has a volume of preferably greater than orequal to 350 cc, more preferably greater than or equal to 380 cc,further preferably greater than or equal to 400 cc, and still furtherpreferably greater than or equal to 420 cc. From the viewpoint of thehead strength, the head preferably has a volume of less than or equal to470 cc.

[3. Measuring Method]

Methods for measuring the specifications are as follows.

[3-1. Club Length Lc]

The club length Lc in the present application is measured in accordancewith the regulation announced by the R&A (the Royal and Ancient GolfClub of Saint Andrews). This regulation is described in “1c. Length” in“1. Clubs” of “Appendix II—Design of Clubs” in the latest Rules of Golfissued by R&A. The measurement method is performed when the club isplaced on a horizontal plane and the sole thereof is set against a planehaving an angle of 60 degrees with respect to the horizontal plane. Thismethod is therefore also referred to as the “60-degree measurementmethod”.

[3-2. Moment of Inertia Ic]

As described above, the moment of inertia Ic is the moment of inertia ofthe golf club 2 about the center of gravity of the golf club 2. Themoment of inertia Ic is the moment of inertia of the golf club 2 aboutan axis line that passes through the center of gravity of the golf club2 and is perpendicular to the shaft center line Z1.

FIG. 7 shows a method for measuring the moment of inertia Ic. As shownin FIG. 7, the golf club 2 is placed on a measuring jig 102 of amoment-of-inertia measuring instrument 100 such that the shaft centerline Z1 is set in the horizontal direction. As the moment-of-inertiameasuring instrument 100, MODEL NUMBER RK/005-002 manufactured byINERTIA DYNAMICS is used. The golf club 2 is placed on the measuring jig102 so that the center of gravity of the golf club 2 is positioned on arotation axis RZ. Thus, the moment of inertia Ic is measured.

EXAMPLES

Hereinafter, effects of the present disclosure are clarified byexamples, but the present disclosure should not be exclusivelyinterpreted based on the descriptions of the examples.

[Sample 5]

A forged face member, and a casted body member, were welded, whereby adriver head made of a titanium alloy was obtained. A shaft 6 wasobtained by the sheet winding method using a plurality of prepregsheets. A rubber composition was heated and pressurized in a mold,whereby a grip was obtained. In the forming of the grip, a foam rubberand a non-foam rubber were used. A part of a grip body portion 8 a ofthe grip was made of a foam rubber. The foam rubber was used in an innerlayer of the grip body portion 8 a. An outer layer of the grip bodyportion 8 a was made of a non-foam rubber. An end cap portion 8 b of thegrip was made of a non-foam rubber. A formed weight body 20 was coveredwith a rubber material, and this was set in a mold, pressurized, andheated, whereby a weight member 10 having a cover member 30 made of avulcanized rubber was obtained. This weight member 10 was attached to abutt portion of the shaft 6, and thereafter, the grip was attached tothe shaft 6, whereby a golf club as shown in FIGS. 1 and 2 was obtained.

[Other Samples]

Other samples were obtained in the same manner as that of Sample 5,except for the specifications shown in Tables 1 to 4 below. Note thatthe weight W1 of the butt end region R1 was adjusted by appropriatelydetermining presence or absence of the weight member, the weight of theweight member, the wall-thickness distribution of the grip, a foamrubber and a non-foam rubber used for the grip. Respective shafts wereproduced in such a manner that a flex was not changed by changing thetypes, shapes, and/or arrangement of prepregs.

Respective specifications and evaluation results of the samples areshown in Tables 1 to 4 below. For comparison, Sample 5 is shown in eachtable. Methods for measuring the specifications are as explained above.

TABLE 1 Specifications and Evaluation Results of Samples Sample SampleSample Sample Sample Sample Sample Unit 1 2 3 4 5 6 7 Club length Lcinch 45.75 45.75 45.75 45.75 45.75 45.75 45.75 Head weight Wh g 196 196196 196 196 196 196 Shaft weight Ws g 40 40 40 40 40 40 40 Grip weightWg g 31 31 31 31 31 31 31 Weight W1 of g 24 27 30 32 34 37 40 butt endregion R1 Weight W2 of g 32 35 38 40 42 45 48 grip-weight portion WeightW3 of g 72 75 78 80 82 85 88 shaft-grip- weight portion Club weight Wc g270 273 276 278 280 283 286 W1/W3 — 0.33 0.36 0.38 0.40 0.41 0.44 0.45Ws/Wc — 0.15 0.15 0.14 0.14 0.14 0.14 0.14 Wg/W2 — 0.97 0.89 0.82 0.780.74 0.69 0.65 W1/Ws — 0.60 0.68 0.75 0.80 0.85 0.93 1.00 Gravity center% 30 29 28 27 27 26 25 ratio T3 of shaft-grip- weight portion Gravitycenter % 35 32 30 28 27 26 24 ratio T2 of grip-weight portion Clubmoment Mc kg · cm 22.80 22.79 22.76 22.74 22.72 22.70 22.67 Flightdistance yard 185 188 189 190 190 190 191 Directional yard 11 11 10 1010 10 9 stability of hit balls Variation in — 6.5 6.3 6.0 5.7 5.5 5.14.8 hitting points

TABLE 2 Specifications and Evaluation Results of Samples Sample SampleSample Sample Sample Sample Unit 8 9 5 10 11 12 Club length Lc inch45.75 45.75 45.75 45.75 45.75 45.75 Head weight Wh g 190 195 196 196 198205 Shaft weight Ws g 40 40 40 45 40 40 Grip weight Wg g 31 31 31 36 3131 Weight W1 of g 34 34 34 28 34 34 butt end region R1 Weight W2 of g 4242 42 37 42 42 grip-weight portion Weight W3 of g 82 82 82 82 82 82shaft-grip- weight portion Club weight Wc g 274 279 280 280 282 289W1/W3 — 0.41 0.41 0.41 0.34 0.41 0.41 Ws/Wc — 0.15 0.14 0.14 0.16 0.140.14 Wg/W2 — 0.74 0.74 0.74 0.97 0.74 0.74 W1/Ws — 0.85 0.85 0.85 0.620.85 0.85 Gravity center % 27 27 27 27 27 27 ratio T3 of shaft-grip-weight portion Gravity center % 27 27 27 27 27 27 ratio T2 ofgrip-weight portion Club moment Mc kg · cm 22.09 22.62 22.72 23.02 22.9423.68 Flight yard 186 188 190 182 189 190 distance Directional yard 1111 10 14 13 13 stability of hit balls Variation in — 4.5 5.1 5.5 7.5 6.86.7 hitting points

TABLE 3 Specifications and Evaluation Results of Samples Sample SampleSample Sample Unit 13 5 14 15 Club length Lc inch 45.75 45.75 45.7545.75 Head weight Wh g 196 196 196 196 Shaft weight Ws g 38 40 45 50Grip weight Wg g 31 31 31 31 Weight W1 of butt g 36 34 29 24 end regionR1 Weight W2 of g 44 42 37 32 grip-weight portion Weight W3 of g 82 8282 82 shaft-grip- weight portion Club weight Wc g 280 280 280 280 W1/W3— 0.44 0.41 0.35 0.29 Ws/Wc — 0.14 0.14 0.16 0.18 Wg/W2 — 0.70 0.74 0.840.97 W1/Ws — 0.95 0.85 0.64 0.48 Gravity center ratio T3 % 26 27 30 33of shaft-grip-weight portion Gravity center % 26 27 31 35 ratio T2 ofgrip-weight portion Club moment Mc kg · cm 22.63 22.72 22.99 23.25Flight distance yard 194 190 189 183 Directional stability of yard 9 1014 17 hit balls Variation in hitting — 4.6 5.5 7.6 9.0 points

TABLE 4 Specifications and Evaluation Results of Samples Sample SampleSample Sample Sample Sample Unit 16 17 18 10 5 19 Club length Lc inch44.75 45.00 45.50 45.75 45.75 46.00 Head weight Wh g 196 196 196 196 196196 Shaft weight Ws g 37 38 39 45 40 41 Grip weight Wg g 31 31 31 36 3131 Weight W1 of butt g 34 34 34 28 34 34 end region R1 Weight W2 of g 4242 42 37 42 42 grip-weight portion Weight W3 of g 79 80 81 82 82 83shaft-grip- weight portion Club weight Wc g 277 278 279 280 280 281W1/W3 — 0.43 0.43 0.42 0.34 0.41 0.41 Ws/Wc — 0.13 0.14 0.14 0.16 0.140.15 Wg/W2 — 0.74 0.74 0.74 0.97 0.74 0.74 W1/Ws — 0.92 0.89 0.87 0.620.85 0.83 Gravity center % 27 27 27 27 27 27 ratio T3 of shaft-grip-weight portion Gravity center % 27 27 27 27 27 27 ratio T2 ofgrip-weight portion Club moment Mc kg · cm 22.09 22.26 22.55 23.02 22.7222.90 Flight distance yard 184 186 189 182 190 189 Directional yard 6 78 14 10 12 stability of hit balls Variation in — 3.0 3.8 4.7 7.5 5.5 6.8hitting points[Evaluation Method]

Evaluations were carried out in the following way.

[Tester]

Ten golfers who were classified in the above-described Category Acarried out tests.

[Flight Distance]

“Flight distance” is a distance traveled by a hit ball up to a pointwhere the hit ball reaches finally, which includes run. Each of theabove-described ten testers shot five golf balls with each club. As toeach sample, the average value of all pieces of flight distance data isshown in Tables above.

[Directional Stability of Hit Balls]

Each of the above-described ten testers shot five golf balls with eachclub. A distance of deviation rightward or leftward from the targetdirection was measured. The distance of deviation is regarded as a plusvalue, irrespective of whether the deviation was rightward or leftward.As to each sample, the average value of the deviation distances is shownin Tables above.

[Variation in Hitting Points]

Hitting points were measured using a shot marker (impact marker). Theshot marker was attached to the face surface of each head, and thepositions of hitting marks on the face surface were measured. Thedistance (off-center distance) of each hitting point from the facecenter was measured. Each of the above-described ten testers shot fivegolf balls with each club, and the hitting point of each shot wasmeasured. The standard deviations of the off-center distances are shownin Tables above.

Regarding the data shown in Table 1, changes in the weight W1 of thebutt end region R1 led to changes in the club moment Mc. As shown in theresults in Table 1, a decrease in the club moment Mc led to theenhancement of the on-plane effect, thereby suppressing the variation inhitting points and making the directional stability of hit ballsexcellent. Further, the on-plane effect and the club weight effectallowed the flight distance to increase, in spite of an increase in theclub weight.

Regarding the data shown in Table 2, the head weight Wh was changed. Asindicated by the results shown in Table 2, even when the head weight Whwas increased and thus the club moment Mc was increased, no decrease wasrecognized in the flight distance, which was achieved by the enhancedclub weight effect and the increased kinetic energy of the head.

Regarding the data shown in Table 3, the weight W1 of the butt endregion R1 was changed, while no change was made in the club weight Wc.As indicated by the results shown in Table 3, the variation in hittingpoints was suppressed and the directional stability of hit balls wasexcellent, which was achieved by the on-plane effect obtained byreduction in the club moment Mc.

Regarding the data shown in Table 4, changes in the shaft length Ls ledto changes in the club length Lc. The deterioration in variation inhitting points was suppressed even with a longer club.

As these evaluation results indicate, the superiority of the presentdisclosure is obvious.

The following clauses are disclosed regarding the above-describedembodiments.

[Clause 1]

A golf club including:

a head;

a shaft including a tip end and a butt end; and

a grip, wherein

the golf club has a length of greater than or equal to 45.0 inches,

the head has a weight of greater than or equal to 195 g, and

the golf club has a club moment Mc about a rotation center of less thanor equal to 22.74 (kg·cm), the rotation center being a point that is 100mm away from a butt end of the grip.

[Clause 2]

The golf club according to clause 1, wherein the shaft has a weight ofless than or equal to 40 g.

[Clause 3]

The golf club according to clause 1 or 2, wherein the golf club has aweight of greater than or equal to 280 g.

[Clause 4]

The golf club according to any one of clauses 1 to 3, wherein a butt endregion has a weight of greater than or equal to 27 g, the butt endregion being a region having a distance from the butt end of the grip ofless than or equal to 100 mm.

[Clause 5]

The golf club according to clause 4, wherein

the golf club further includes a weight member located in the butt endregion,

the grip and the weight member constitute a grip-weight portion, and

the grip-weight portion has a weight of greater than or equal to 40 g.

The foregoing description describes only examples, and various changescan be made without departing from the essence of the presentdisclosure.

What is claimed is:
 1. A golf club comprising: a head; a shaft includinga tip end and a butt end; and a grip, wherein the golf club has a lengthof greater than or equal to 45.0 inches, the head has a weight ofgreater than or equal to 195 g, the golf club has a club moment Mc abouta rotation center of less than or equal to 22.74 (kg·cm), the rotationcenter being a point that is 100 mm away from a butt end of the grip, abutt end region has a weight of greater than or equal to 27 g, the buttend region being a region having a distance from the butt end of thegrip of less than or equal to 100 mm, the golf club further includes aweight member located in the butt end region, the grip and the weightmember constitute a grip-weight portion, the grip-weight portion has aweight of greater than or equal to 40 g, and the grip-weight portion hasa gravity center ratio T2 of less than or equal to 28%, the gravitycenter ratio T2 of the grip-weight portion being calculated by thefollowing formula: T2=(D2/L2)×100, where D2 represents a distance fromthe butt end of the grip to a center of gravity of the grip-weightportion, and L2 represents a length of the grip.
 2. The golf clubaccording to claim 1, wherein the shaft has a weight of less than orequal to 40 g.
 3. The golf club according to claim 1, wherein the golfclub has a weight of greater than or equal to 280 g.
 4. The golf clubaccording to claim 1, wherein the grip has a weight of less than orequal to 35 g.
 5. The golf club according to claim 1, wherein the griphas a weight of less than or equal to 33 g.
 6. The golf club accordingto claim 1, wherein the grip has a weight of less than or equal to 31 g.7. The golf club according to claim 4, wherein the grip includes a gripbody portion that has a cylindrical shape, and an end cap portion thatcloses an opening of the grip body portion on one end side and forms abutt end face of the grip, and a part of the grip body portion is madeof a foam rubber.
 8. The golf club according to claim 4, wherein thegrip includes a grip body portion that has a cylindrical shape, and anend cap portion that closes an opening of the grip body portion on oneend side and forms a butt end face of the grip, and the end cap portionis made of a non-foam rubber exclusively, and the grip body portionincludes a foam rubber portion made of a foam rubber.
 9. The golf clubaccording to claim 4, wherein the grip includes a grip body portion thathas a cylindrical shape, and an end cap portion that closes an openingof the grip body portion on one end side and forms a butt end face ofthe grip, and the end cap portion has a specific gravity greater than anaverage specific gravity of the grip body portion.
 10. The golf clubaccording to claim 4, wherein the weight member has a length in an axialdirection of greater than or equal to 5 mm and less than or equal to 50mm.
 11. The golf club according to claim 4, wherein a distance between atip-end-side end of the weight member and the butt end of the grip isgreater than or equal to 15 mm and less than or equal to 70 mm.
 12. Agolf club comprising: a head; a shaft including a tip end and a buttend; and a grip, wherein the golf club has a length of greater than orequal to 45.0 inches, the head has a weight of greater than or equal to195 g, the golf club has a club moment Mc about a rotation center ofless than or equal to 22.74 (kg·cm), the rotation center being a pointthat is 100 mm away from a butt end of the grip, a butt end region has aweight of greater than or equal to 27 g, the butt end region being aregion having a distance from the butt end of the grip of less than orequal to 100 mm, the golf club further includes a weight member locatedin the butt end region, the grip and the weight member constitute agrip-weight portion, the grip-weight portion has a weight of greaterthan or equal to 40 g, the shaft, the grip, and the weight memberconstitute a shaft-grip-weight portion, and W1/W3 is greater than orequal to 0.40, where W1 represents the weight (g) of the butt endregion, and W3 represents a weight (g) of the shaft-grip-weight portion.13. The golf club according to claim 12, wherein a distance between acenter of gravity of the shaft and the butt end of the shaft is lessthan or equal to 550 mm.
 14. The golf club according to claim 12,wherein the shaft-grip-weight portion has a gravity center ratio T3 ofless than or equal to 27%, the gravity center ratio T3 of theshaft-grip-weight portion being calculated by the following formula:T3=(D3/L3)×100, where D3 represents a distance from the butt end of thegrip to a center of gravity of the shaft-grip-weight portion, and L3represents a distance from the butt end of the grip to the tip end ofthe shaft.
 15. The golf club according to claim 12, wherein the golfclub has a length of less than or equal to 46.0 inches.